01 NRDC Dyslexia 1-88 update - Texthelp

Developmental dyslexia in adults: a research review 69
consequence of dynamic and recursive interactions within the neurological system. These
interactions may take place in response to either biological or environmental stimuli. Taking
the brain’s plasticity (or capacity for reorganisation) into account, the model anticipates
exponential effects from initial conditions. Once again, the concept of a ‘specific’ learning
disability does not capture the dynamic interplay between the system’s various components.
Third, the system is not linear but complex. Linear models of learning disability assume a
closed-circuit relationship between brain functioning and behaviour, which in turn suggests
direct causal links. We now know that this is not what happens in an open neurological
system, where the components interact in a nonlinear, dynamic fashion. Although research
into dyslexia has been dominated by linear causal models which then recursively advance the
concept of ‘specific’ disability, it is clear that all disabilities become more pervasive over time,
even those that appeared specific at the outset of development.
In this way, there are adverse developmental outcomes. At some point a specific deficit begins
to have more generalised effects on processes that underlie a broader range of tasks than
reading alone. There are both cognitive consequences and motivational side effects, so that
the performance deficits are increasingly global (Stanovich, 1986). According to the selforganising
systems model, an inefficiency in processing might begin as a specific deficit but
then become global, as underutilisation of a dysfunctional part of the brain leads to
overactivation of intact brain areas and to aggravation of any imbalance; repeatedly
maladaptive patterns of mental activity may create constraints for future learning; and brain
areas that are activated to compensate for the dysfunctional area may come to perform their
original functions less efficiently, even though there might be no essential relationship
between the two functions.
Tutors often encounter students whose reading problems overlap with impairments in the
executive functions of attentional switching, selective attention, sustained attention and
working memory. The self-organising systems model suggests that working memory and
reading problems aggravate each other and that both might originate in phonological
processing problems, in which case a working memory problem might be alleviated by an
improvement in reading.
Few practitioners and diagnosticians of learning disabilities have a sufficiently comprehensive
understanding of the neurological system to be able to interpret disabling conditions from this
perspective (Zera, 2001). However, if they were to gain such an understanding, the model
suggests that their remediation strategies might then take into account the ways in which a
supposedly specific disability interacts with other parts of the neural system and strategies of
this kind might lead to greater success in alleviating the related symptoms of dysfunction.
The self-organising systems model is compatible with the three-level model, although it
entails a more complex view of causality than implied by that model. It does not challenge the
idea of a developmental dysfunction resulting from an innate biological constraint, but it does
challenge the notion that, regardless of how specific such a constraint might have been, the
behavioural outcome itself could remain specific (see also Stanovich, 1986).